Water handling equipment capable of detecting operation by a user by utilizing a switch or a sensor, and switching between spouting and water stop or changing a spouting form on the basis of the detected operation begins to spread. Such water handling equipment such as faucet apparatuses used in a water section such as a kitchen, a washroom, a toilet and a bathroom are used in environment where water wetting is likely to be caused, are extremely heavily-used, and are required to have a long term usability life. Therefore, a switch or a sensor for detecting operation desirably does not have a mechanical electrical contact.
A photoelectric sensor utilized in an automatic faucet or the like has an advantage that operation can be performed in a non-contact state. However, a sensing unit is stood out, and therefore it cannot be said that designability is excellent. Furthermore, the photoelectric sensor has a problem in that when water or bubbles are attached to the sensing unit, malfunction is caused.
Additionally, although an electrostatic sensor can be operated by a very light touch, in the environment where water wetting is likely to be caused, malfunction cannot be avoided, and the electrostatic sensor is difficult to be utilized in the water handling equipment.
Furthermore, faucet parts being conductors require insulation by resin or the like, and it cannot be said that designability is excellent.
Herein, for example, Patent Document 1 (Japanese Patent Unexamined Publication No. 54-153284) describes a piezoelectric switch. This piezoelectric switch is a switch that utilizes a piezo-electric element, and can detect pressing operation of a user without utilizing a mechanical electrical contact.
Patent Document 2 (Japanese Patent Unexamined Publication No. 58-40803) describes a contactless push button switching circuit. Also in this push button switch, a piezo-electric element is utilized, and pressing operation by a user is detected without using a mechanical electrical contact.
However, in the piezoelectric switch described in the above Patent Document 1, pressing force applied to the piezo-electric element is used to cause elastic deformation, and switch operation is detected by means of charges generated on the basis of this elastic deformation. Therefore there is a problem in that relatively large operating force is needed in order to operate switch, and operation cannot be performed by a light touch.
In the contactless push button switching circuit described in Patent Document 2, the piezo-electric element is incorporated in an oscillation circuit, and pressing operation by a user is detected by utilizing lowering or stop of oscillation due to change in electrical characteristics such as impedance of the piezo-electric element caused by pressing force applied to this piezo-electric element. In this contactless push button switching circuit, even slight pressing force to the piezo-electric element causes change in the electrical characteristics, and an oscillation state of the oscillation circuit incorporated in the piezo-electric element is changed, and therefore operation can be detected even with a light touch.
However, the oscillation state of the oscillation circuit is extremely sensitive to a circuit constant, and therefore there is a problem in that when the piezo-electric element for detecting operation is installed at a place away from an oscillation circuit body, the oscillation state becomes unstable, and misdetection is likely to occur.
For example, in a case where only the piezo-electric element incorporated in the oscillation circuit is disposed in the vicinity of a spouting portion of a faucet apparatus, other part (oscillation circuit body) of the oscillation circuit is disposed on a lower side of a counter board where the faucet apparatus is installed, a lead wire that connects the piezo-electric element and the oscillation circuit body becomes relatively long. Therefore, inductance or a stray capacitance component of this lead wire sometimes makes operation of the oscillation circuit unstable to cause malfunction. In order to prevent such malfunction, the piezo-electric element needs to be disposed in the vicinity of the oscillation circuit body. In this case, for example, the whole of the oscillation circuit needs to be incorporated in the vicinity of the spouting portion in order to dispose an operating unit in the vicinity of the spouting portion of the faucet apparatus, and the degree of freedom of the design of the faucet apparatus is largely restricted.
The present inventors utilize an ultrasonic element, which has been utilized to detect an object located at a distance to some extent, as a touch sensor in order to enable operation by a light touch and to implement prevention of malfunction even in a case of use in water handling equipment, and focuses detection of reverberation or damping of vibration when contact portion is touched during touch operation.
In a touch detection device utilizing such an ultrasonic element as a touch sensor, the ultrasonic element as a vibration excitation element needs to be electrically connected by an electrical wire, and therefore potting by resin or the like is needed in order to utilize the touch detection device in a water section.
However, when the ultrasonic element is directly potted, the ultrasonic element cannot be vibrated, and therefore a problem is that the ultrasonic element needs to be potted while a space enabling vibration is secured.
Furthermore, in a case where such an ultrasonic element is incorporated in water handling equipment, even when the ultrasonic element is potted with a potting layer while the space enabling vibration is secured, there is a problem in that a temperature difference or an air pressure difference between an internal space on a side close to the ultrasonic element with respect to the potting layer and an external space of the potting layer is likely to be caused by a using situation of hot water or water of the water handling equipment, or temperature change due to an ambient environment.
Therefore, there is a problem in that, for example, gas containing vapor in the external space of the potting layer comes through an electrical wire to be drawn in the internal space on the side close to the ultrasonic element by the air pressure difference between the inner and outer spaces with such a potting layer therebetween, and the ultrasonic element is exposed to moisture, and functionality may be lowered.